Wang L F, Doi R H
Nucleic Acids Res. 1986 May 27;14(10):4293-307. doi: 10.1093/nar/14.10.4293.
The gene coding for Bacillus subtilis RNA polymerase major sigma 43, rpoD, was cloned together with its neighboring genes in a 7 kb EcoRI fragment. The complete nucleotide sequence of a 5 kb fragment including the entire rpoD gene revealed the presence of two other genes preceding rpoD in the order P23-dnaE-rpoD. The dnaE codes for DNA primase while the function of P23 remains unknown. The three genes reside in an operon that is similar in organization to the E. coli RNA polymerase major sigma 70 operon, which is composed of genes encoding small ribosome protein S21 (rpsU), DNA primase (dnaG), and RNA polymerase sigma 70 (rpoD). There is a relatively high degree of base and amino acid homology between the DNA primase and sigma genes. The most significant differences between the two operons are observed in the molecular size of the first genes (P23 and rpsU), the complete lack of amino acid homology between P23 and S21, the molecular weights of the two rpoD genes, the size of the intercistronic region between the first two genes, and the regulatory elements of the operon.
编码枯草芽孢杆菌RNA聚合酶主要σ因子43（rpoD）的基因与其相邻基因一起被克隆到一个7 kb的EcoRI片段中。一个包含完整rpoD基因的5 kb片段的完整核苷酸序列显示，在rpoD之前按P23-dnaE-rpoD的顺序存在另外两个基因。dnaE编码DNA引发酶，而P23的功能仍然未知。这三个基因位于一个操纵子中，其组织形式与大肠杆菌RNA聚合酶主要σ因子70操纵子相似，后者由编码小核糖体蛋白S21（rpsU）、DNA引发酶（dnaG）和RNA聚合酶σ因子70（rpoD）的基因组成。DNA引发酶基因和σ因子基因之间存在较高程度的碱基和氨基酸同源性。两个操纵子之间最显著的差异体现在第一个基因（P23和rpsU）的分子大小、P23和S21之间完全缺乏氨基酸同源性、两个rpoD基因的分子量、前两个基因之间的基因间区域大小以及操纵子的调控元件上。
